The invention relates to a bipolar medical instrument for cutting tissue comprising a first working element and at least one second working element, which are arranged adjacent to one another at a distal end of the instrument. The first working element and the second working element are configured as an electrode connectable to high frequency power and a counter electrode.
Such an instrument is disclosed in the German catalogue of the company Karl Storz GmbH and Co. KG, Tuttlingen, xe2x80x9cSTORZ Karl Storz-Endoskopexe2x80x9d, Vol. xe2x80x9cLaparoskopiexe2x80x9d, 3rd Edition 1/1999, page BI-COA 10/2. Such a bipolar medical instrument is used for example in laparoscopic surgery for treating tissue in the human or animal body.
Incisions are made in the tissue being treated and cause bleeding, which must be stopped.
In the known instrument, bipolar high frequency power is used only for stopping bleeding, i.e. for coagulation. The placement of incisions in the tissue takes place mechanically, namely with a scalpel-like knife.
The known instrument mentioned before comprises a first working element in the form of a jaw and a second working element also in the form of a jaw, where the jaws are arranged side by side at a spacing from one another, in other words like a pair of forceps. The jaw forming the first working element is formed as an electrode which can be supplied with high frequency power and the jaw forming the second working element is formed as a counter electrode. The first jaw can be connected with a corresponding electric line to one pole of a high frequency voltage source and the second jaw can be connected through a corresponding electric line to the other pole of the high frequency voltage source. The first jaw and the second jaw are insulated from one another due to their spacing.
A comparable instrument is disclosed in WO 97/17033. When switching on the high frequency source, a current flux develops in the tissue between the first jaw and the second jaw, so that the coagulation effect is limited to the region between the two sets of jaws. To coagulate a vessel, the vessel is grasped to extend transversely to the jaw.
The cutting function of this known instrument for cutting tissue, in particular for cutting through vessels present in the tissue, is realized with a scalpel -like knife arranged between the first jaw and the second jaw. The knife can be projected forwardly in axial direction by actuating a separate handle at the proximal end of the instrument, for example to cut through a vessel which is grasped to extend transversely to the sets of jaws. The cutting effect of the knife is purely mechanical. By providing the knife between the first and second jaws, the insertion of an additional cutting tool, for example a cutter or a scalpel, into the operation area is avoided as well as the associated exchange of instruments in comparison to other conventional bipolar instruments having only the coagulation function.
Even so, the configuration of this known instrument with the scalpel-like knife for cutting tissue is of disadvantage when the dimensions of the instrument are to be reduced, i.e. when the instrument is to be constructed as small as possible. The known instrument has a diameter of about 10 mm, while a diameter of such instruments of about 5 mm is desirable for some applications.
Reducing the diameter of the known instrument from 10 mm to 5 mm is however not possible for the following reasons. The scalpel-like knife must be placed between the first jaw and the second jaw, so that the first jaw and the second jaw of the known instrument already have a diameter of only 3 mm and are spaced from one another by about 3 mm. A reduction of the total diameter of the arrangement of the first jaw, the second jaw and the scalpel-like knife to 5 mm would require the reduction of the diameter of the first jaw and the second jaw to less than 1 mm. The stability of the jaws, which make up the working elements, is however no longer ensured with such dimensions. A reliable treatment of the tissue with the instrument requires a sufficient stability of the first and second working elements.
A further instrument is disclosed in the mentioned German catalogue on page BI-COA 5/12, which is a grasping and coagulation instrument without a cutting function. Its working element comprises an upper and a lower jaw part. The two jaw parts are configured as a grasping tool and also as an electrode and counter electrode, so that current can flow for coagulation between the jaw parts through the tissue grasped there between.
The present invention however is not limited to improving an instrument that is limited to grasping and coagulation functions. Therefore, the term xe2x80x9cworking elementxe2x80x9d will be understood generally in the present invention, as long as the working elements constitute an electrode and a counter electrode independent of their shape or other functions.
Generally, the object of the present invention is to provide a bipolar instrument for cutting tissue of the above- mentioned type, by which the cutting function is realized in a manner, which is not mechanical.
The object is achieved by a bipolar medical instrument for cutting tissue, comprising:
a shaft having a distal end and a proximal end;
a first working element disposed at said distal end of said shaft, said first working element being configured as an electrode connectable to high frequency current;
at least one second working element disposed at said distal end of said shaft and adjacent to said first working element, said at least one second working element forming a counter electrode with respect to said first working element,
wherein at least one of said first working element and said second working element comprises at least one projection, which is directed toward the other of said first and second working elements, and a free end of said at least one projection is configured such that a concentration of the current density occurs at said free end.
The advantageous effect of concentrating the current density in the present instrument is that an incision can be made in the tissue or a vessel in the tissue can be cut off using electrical energy. Compared to the known instrument, the function of cutting is therefore not realized with a mechanical cutting instrument, such as a scalpel-like knife, but with an xe2x80x9celectric bladexe2x80x9d. The placement of an incision with the present instrument is guided by hand such that the xe2x80x9celectric cutterxe2x80x9d formed between the at least one projection and the other working element is moved through the tissue or through the vessel. The cutting process itself takes place substantially without contact.
Although the invention is not limited to improving the mentioned conventional instrument, also the use of the present invention with this known instrument has the particular advantage that the jaw forming the first working element and the jaw forming the second working element can be formed with larger diameter and therefore are more stable due to the lack of a mechanical cutting instrument between the two sets of jaws in the known instrument. This is the case, even when the total diameter of the instrument should be reduced, for example to 5 mm. In this case, the further advantage results with the present configuration of the invention, that no further handle need be provided on the instrument for cutting the tissue, as is the case in the known instrument, where the scalpel-like knife is moved back and forth. In contrast, the cutting procedure in the present instrument takes place with the working elements themselves, so that the constructive complexity of the present instrument is advantageously reduced.
In a preferred embodiment, both the first working element and the second working element comprise at least one projection.
The feature advantageously leads to increased concentration of the current density between the first and second working elements, where the electric cutting effect can be further improved.
Preferably, the at least one projection of the first working element stands opposed to the at least one projection of the second working element.
The advantage is that the cutting line, defined by the opposing projections, is very precisely defined. The projections can be oppositely disposed in axial direction of the working elements or in a transverse or perpendicular direction. For example, cutting can be performed when the projections are disposed oppositely in perpendicular direction by an axial shifting of the instrument or by a transverse movement with respect to the axial direction of the working elements. When the projections are disposed oppositely in axial direction, cutting can be performed by rotating the instrument about its longitudinal axis.
Preferably, the first working element extends beyond the second working element in axial direction of the working elements and the projections are oppositely disposed in the axial direction of the working elements.
In a further preferred embodiment, the free end of the at least one projection is configured as a point.
With this configuration of the free end as a point, particularly high current densities and therefore a particularly good cutting effect can be achieved du e to the effect of the pointed free end. In addition, the xe2x80x9celectric bladexe2x80x9d defined by the at least one projection can be particularly precisely defined.
The free end of the at least one projection can however also be formed as an edge running transversely to the working element direction to be able to better cut through the entire thickness of the tissue located between the first working element and the second working element. This can also be achieved in that a projection is arranged on each of the two working elements at about the same axial position, whose free ends are also formed as points as described above.
In a further preferred embodiment, the at least one projection can also be rounded.
In this embodiment, a high current density is not achieved as with the pointed projection, however the electric cutting effect can advantageously be expanded to a strip corresponding to the width of the rounded free ends.
A particularly sharp and wellxe2x80x94defined short incision can be made advantageously when the free end of the at least one projection of the first working element and the free end of the at least one projection of the second working element have a minimal spacing with respect to one another, because the current flow is then optimally concentrated with high density in the short path between the projections. xe2x80x9cMinimalxe2x80x9d spacing means that the spacing of the working elements in the region of the projections is smaller than that in the remaining regions of the working elements. For example, a minimal spacing can be about 1 mm or less.
The free end of the at least one projection can preferably be configured as an elongated edge.
Further preferred is when at least one projection runs as a wedge with an inclination in the axial direction of the working element. It is also preferred to provide both the first working element and the second working element with at least one projection formed as an elongated edge, where the edges are each sloped with respect to the axial direction of the working elements and where the slopes of the opposing edges run counter directionally.
As can be taken from above, an electric cutting of the tissue along a defined cutting line is made possible by a corresponding selection of the arrangement of the at least one projection, preferably several projections. In the scope of the present invention, it is therefore possible to generate one or more defined cutting lines for electric cutting by correspondingly selecting the number and position of one or more projections.
A particularly advantageous adaptation of the present instrument to the given application is made possible in that the first working element and the second working element are both exchangeable. Thus, different working elements with a corresponding number and distribution of the projections can be made available.
In a constructively particularly simple embodiment of the present invention, the first working element and the second working element are preferably arranged to be immovable on the distal end of one or two rod-shaped elements.
In this manner, a purely bipolar cutting instrument is advantageously provided, which can be used as a type of scalpel or knife for cutting tissue or for cutting through vessels. The difference however is that the cutting effect is produced electrically instead of mechanically. Preferably, the rod-shaped element or the rod- shaped elements are configured themselves to conduct electricity.
A constructively simple arrangement of the present instrument is achieved thereby, because no separate wires are necessary for supplying electricity. The at least one rod-shaped element or the rod-shaped elements can be equipped with a simple handle for manipulation at the proximal end.
It is however also preferred that the first working element and the second working element are each formed as jaws, where the first set of jaws and the second set of jaws are arranged side by side at a spacing from one another, and where each set of jaws comprises two jaw parts moveable relative to one another between which the tissue can be grasped and coagulated.
This advantageous embodiment represents an improvement of the above-mentioned known grasping, coagulating and cutting instrument, where according to the invention, the scalpel-like knife provided between the first and second sets of jaws in the known instrument is now replaced according to the present invention by the at least one projection and the electric cutting effect produced therewith. With this instrument, tissue can first be grasped and coagulated between the jaw parts. To subsequently apply an incision or to cut through a vessel, the jaw parts are opened and the instrument is withdrawn by a small amount. The jaw parts are closed and the instrument is then guided such that the xe2x80x9celectric bladexe2x80x9d formed between the at least one projection of one jaw and the other jaw passes through the tissue and cuts same.
In a further preferred embodiment, the at least one projection is arranged on the first jaw part of one jaw and a second projection is arranged on the second jaw part of the same jaw.
The advantage is that an xe2x80x9celectric bladexe2x80x9d, is formed having a spatial and not only linear extension between the two working elements of the instrument when the jaw parts are closed or even more so when the jaw parts are slightly opened. Particularly advantageous is when the other jaw also comprises at least two projections, of which one projection is on the first jaw part and the second projection is on the second jaw part of the other jaw.
In a further preferred embodiment, the at least one projection of the first jaw is arranged on one first jaw part and the at least one projection of the second jaw is arranged on the jaw part of the second jaw which lies diametrically opposite to the first jaw part of the first jaw.
In this embodiment, a cutting line is achieved which runs at an inclination with respect to the main plane (horizontal plane) defined by the first and second jaws.
Preferably, the at least two projections in the above two embodiments are arranged at the same location along the axial direction of the working elements.
The advantage of this arrangement is that a precise incision can be made from both sides in a given piece of tissue.
Further advantages of the invention will become apparent from the following description and the appended drawings. It will be understood that the above-mentioned features and those to be discussed belong are applicable not only in the given combinations, but may also be used in other combinations or taken alone without departing from the scope of the present invention.